For the commercial preparation of Ethernet-based connection services, so-called Service Level Agreements are usually a central component of the contract between the network operator or service provider and the customer. Such Service Level Agreements describe in detail a minimum continuous performance of data transmission or service to be guaranteed by the network operator or service provider to the fixed demarcation line, that is, typically to the point at which the data or the service is transferred to the application device of the customer or is fed from this device onto the transmission link. To guarantee a certain performance of such a service or a certain quality of the data transmission, the continuous digital monitoring of the data transmission or the protocol at the demarcation line is necessary. This is realized according to known methods usually through the use of active transmission technology at the demarcation line, that is, at the customer site, and through the measurement and evaluation of digital performance data, such as, e.g., “loss of Ethernet frame” or the like. The performance data is then typically transmitted via an additional transmission channel from the customer site to the location of the network operator.
This type of active performance monitoring allows the verification and guaranteeing of compliance with agreements set down in Service Level Agreements. In addition, in this way a detailed error analysis is possible in the case of a fault.
However, the use of active transmission technology for determining performance data at a demarcation line, especially for the purpose of monitoring special services, leads to an increase in the hardware and software costs, as well as to an increase of the operating costs due to the necessary maintenance and commissioning of the active transmission technology at the customer site. In addition, network availability decreases due to the ever-present failure probability of active transmission technology.